Method of producing diamond and/or diamond-like modifications of boron nitride

ABSTRACT

A method of producing diamond and/or diamond-like modifications of boron nitride from a material to be transformed, such material being carbon and/or boron nitride, with the use of explosive power, said explosive power being used by way of performing detonation of a charge comprising an explosive and a material to be transformed.

FIELD OF THE ART

The present invention relates to the art of producing superhardmaterials and more particularly to methods of producing diamond and/ordiamond-like modifications of boron nitride.

DESCRIPTION OF THE PRIOR ART

Compression of substances by shock waves leads to the origination ofhigh dynamic pressures and high temperatures and produces substances(target products) in the form of high-pressure phases featuring highhardness. Thus, shock compression of graphite to pressures exceeding 20GPa produces a diamond (Science, vol. 133, No. 3467, published in June,1961. American Association for the Advancement of Science, Washington),P. S. De Carlie, J. C. Jamieson "Formation of Diamond by ExplosiveShock", pp. 1821-1822).

Impact compression of boron nitride to pressures exceeding 12 GPaproduces a dense modification of this compound (Doklady Akademii NaukSSSR, vol. 172, No. 5, published in February, 1967, "Nauka" Publishers,Moscow: C. A. Adadurov, Z. G. Aliev, L. O. Atovmyan, T. V. Bavina, Yu.G. Borodko, O. N. Breusov, A. N. Dremin, A. Kh. Muranevich, S. V.Pershin, "Formation of Wurtzite-like Modification of Boron Nitridethrough Impact Compression", pp. 1066-1068).

Methods are known in the art of producing superhard materials--diamondand/or diamond-like modifications of boron nitride, according to whichmaterials to be transformed--graphite and/or hexagonal boron nitride areplaced into sturdy metallic containers, so-called conservation ampoules,of flat or cylindrical type, in the walls of which shock waves aregenerated by detonating explosive charges found in contact with thewalls of the ampoule, or by impacting the walls of such ampoules withbodies accelerated by detonation products to considerable speeds. Shockwaves from the walls of the ampoules enter into the material beingtransformed and compress it until the required pressures andtemperatures originate in it. For increasing the yield of the targetproduct, other substances are usually added to the material beingtransformed, e.g. metals which upon impact compression are heated to asmaller extent than the resulting high-pressure phase (the targetproduct). As a result, these additives reduce the temperature of thehigh-pressure phase and preclude annealing of said phase and itsconversion to the initial state (U.S. Pat. No. 3,401,019, published onSept. 10, 1068, Class 23-209.; UK Pat. No. 1,281,002, Class COIB 31/06,published on July 12, 1972).

Also known is a method of producing superhard materials, according towhich shock waves in the mixture of the material to be transformed andcooling additions are generated by the detonation of a charge found incontact with the surface of the mixture, or by an impact on such surfaceby a body accelerated by the products of explosion. In this case themixture of the initial phase with the cooling addition resides in thecavity of a solid and sturdy metallic support, preventing the substancebeing treated from scattering (UK Pat. No. 1,115,648, published on May29, 1968, Class COIB 31/06).

All the known methods for creating high dynamic pressures andtemperatures use impact compression to transform the materials, whichare placed in solid metallic specially manufactured containers(ampoules), which are not reusable and are either demolished when openedor destroyed upon the explosion, as in the last-cited method. All theabove-cited methods require labor-consuming operations for themanufacture and opening of the ampoules, as well as the consumption oflarge amounts of structural materials and explosives.

DISCLOSURE OF THE INVENTION

The present invention is directed to a method of producing diamondand/or diamond-like modifications of boron nitride from a material to betransformed--carbon and/or boron nitride through the use of explosivepower, and conditions for the process which allow for the production ofthese superhard materials without the use of expendable conservationcontainers, and with less costly and simpler of the synthesis processequipment and instrumentation.

Said object is accomplished by a method of producing diamond and/ordiamond-like modifications of boron nitride from a material to betransformed--carbon and/or boron nitride with the use of explosivepower, the explosive power, according to the invention, being utilizedby detonating a charge comprising an explosive and the material to betransformed.

In the method of the invention the charge is detonated in a hollowcontainer manufactured from steel, tightened prior to the explosion, andhaving a volume to ensure a sufficient degree of expansion of gaseousdetonation products and small residual gas pressures (1 to 5 atm). Thismakes the container non-expendable and reusable for as many as thousandsand even dozens of thousands of times, ruling out the application ofspecial expendable conservation ampoules, the consumption of structuralmaterials thus being substantially reduced. The present invention alsomakes it possible to have a substantial reduction in the consumption ofexplosives (by a factor of 10 to 30), since the latter are in directcontact with the material to be transformed, and there is no necessityin creating shock waves of long duration, as in the prior art methods.

The present method also makes it possible:

(a) to obtain target products with a high yield (up to 20%);

(b) to purposefully obtain diamond powders featuring a uniformfractional composition, including submicron fractions with particles notover 1 μm in size, without additional operations of fractionation;

(c) to purposefully obtain diamond-like modifications of boronnitride--wurtzite or, mainly, cubic ones.

Superhard materials produced by the present method may be used both asabrasives and as starting materials for producing polycrystallinecompacts from which cutting tools are manufactured.

According to the invention, materials to be transformed are subjected tothe action of high dynamic pressures and high temperatures developingdirectly in the detonation wave of condensed explosives, namely in thefront of the detonation wave, in the reaction zone, and in thedetonation products containing, mainly, CO, CO₂, C, H₂ O, and N₂.

In the present method the pressure and temperature ranges are determinedby the qualitative and quantitative composition of the charge and dependmainly on the nature of the explosive, its power and density.

It is expedient to use as explosives, substances which upon detonationof a charge, provide dynamic pressures of 3 to 60 GPa and temperaturesof 2000° to 6000° K. Such substances are, e.g.cyclotrimethylenetrinitramine (hexogen),cyclotetramethylenetetranitramine (octogen), trinitrotoluene (trotyl),trinitrophenylmethylnitramine (tetryl), pentaerythritol tetranitrate(PETN), tetranitromethane (TNM) or mixtures of said explosives. Maximumpressure is determined by the pressure in the chemical peak of thedetonation wave, which for hexogen having a density of 1.8 g/cm³ is 60GPa. Minimum pressure is determined by the pressure in the end of thereaction zone, which for trotyl having a density of 0.8 g/cm³ is 3.0GPa. The above-cited temperature ranges are determined by thetemperatures developed in the detonation of a high-power explosive witha minimum quantity of material to be transformed and in the detonationof a mixture of a high-power explosive with a maximum quantity ofmaterial to be transformed (F. A. Baum, L. P. Orlenko, K. P.Stanyukovich, V. P. Chelyshev, B. I. Shekhter, "Fizika vzryva"/`Physicsof Explosion`/, published in 1975, "Nauka" Publishers, Moscow, pp.97-125, 145-152).

It is essential that very high temperatures (4500 to 6000° K.) lead tomelting the material to be transformed in the reaction zone, if thismaterial is used in the form of a fine-dispersed fraction with particlesizes less than 1 μm, and to the obtaining of fine-dispersed fractionsof desired products. It is also essential that in the flying asunder ofthe explosion products containing particles of the desired product theiradiabatic cooling rate is ˜10⁸ deg/sec, thus substantially diminishingthermal annealing of the desired products and their graphitization.

The present method envisages the use of charges containing 30 to 99 mass% of an explosive and 1 to 70 mass % of a material to be transformed.

With a view to precluding chemical interaction of the material to betransformed with heated detonation products and to preserving thedesired product in the detonation products, it is recommended that thecharge contain, in addition to an explosive and the material to betransformed, also additives inert to the material to be transformed,which evaporate or decompose beyond the front of the detonation wave inan amount of 1 to 50% of the charge mass. Such inert additives as water,ice, liquid nitrogen, aqueous solutions of salts of metals, and crystalhydrates are decomposed or evaporated with absorption of heat, bringdown the temperature of detonation products, and thus help to preservethe desired product in the detonation products. Such substances asammonium salts, hydrazine, hydrazine salts, aqueous solutions ofhydrazine salts, liquid or solid hydrocarbons, upon evaporation ordecomposition yield gaseous products which are chemically inert to thematerial being transformed, and not only cool the detonation products,but dilute them, also contributing to the preservation of the desiredproduct.

Moreover, the present method envisages the use of a charge, containing,in addition to an explosive and the material to be transformed,additives which are inert to the material to be transformed: metals orsalts of metals having a density over 2.2 g/cm³. In this manner theconditions of cooling the target product are improved, and the averagepressure in the reaction zone is also increased, even if low-powerexplosives are employed. Moreover, if in said case the material to betransformed is graphite modification of carbon, it is possible toproduce diamond with a bimodal distribution of particles according totheir size (approximately 0.05 to 1.0 and 0.2 to 5.0 m).

The present method envisages the use of charge components not only inthe form of fine-dispersed fractions, but also in the form of granulesprepared from at least one component of the charge or from variouscombinations of its components. The granules may have various sizes andshapes; such as cylinders, disks, spheres, cubes, etc.

For producing diamond with a particle size of 0.05 to 5 μm, it isrecommended that the graphite should be hexagonal graphite, rhombohedralgraphite, colloidal graphite, and pyrolytic graphite.

For producing fine-dispersed fractions of diamond with a particle sizeof 0.01 to 1.0 μm it is advisable to use X-ray-amorphous forms ofcarbon, such as carbon black, vitreous coal coke, schungite, and sugarcarbon.

As the starting boron nitride it is advisable to use its hexagonalmodification or turbostratic form.

The present method envisages the use of a shell manufactured from asubstance inert to the material to be transformed, that is soluble inwater, acids and alkalies. A charge is enclosed in the shell beforedetonating it. The shell contributes to prolongation of the time ofaction of high pressures and temperatures on the material to betransformed upon detonation of the charge, this leading, e.g. in thecase of boron nitride being used, to the formation of itshigh-temperature cubic structure modification. If the shell is made fromsuch substances as salts of alkali metals, carbonates of alkali metals,oxides of metals, then, as a result of detonation, the shell is brokeninto the minutest particles which are easy to remove from the detonationproducts.

The present method envisages detonation of the charge in an atmosphereof air. It is expedient, however, that the charge detonation be effectedin the medium of a gas inert to the target products, in the atmosphereof gaseous detonation products, or in a vacuum of 10⁻⁴ to 10 mm Hg. Withthese conditions observed, the yield of the target product is increased,since interaction of the target product with air oxygen is precluded.

The essence of the invention resides in direct utilization of highdynamic pressures (preferably of 3 to 60 GPa) and high temperatures(preferably of 2000° to 6000° K.) developed in detonation of condensedexplosives with a view to producing diamond and/or diamond-likemodifications of boron nitride. The method is performed by detonating acharge consisting of an explosive and a material to be transformed, andalso, when necessary, of additives which are inert to the material beingtransformed and to the target products. As said additives it is possibleto use water, ice, liquid nitrogen, aqueous solutions of salts ofmetals, such as sodium chloride, calcium chloride; crystal hydrates,e.g. CuCl₂.2H₂ O, CaCl₂.6H₂ O; ammonium salts, e.g. ammonium chloride,ammonium nitrate, ammonium oxalate; hydrazine, hydrazine salts, e.g.hydrazine nitrate, hydrazine sulphate; aqueous solutions of hydrazinesalts, such as hydrazine nitrate, hydrazine chloride; liquidhydrocarbons, e.g. octane, benzene, nitrobenzene; solid hydrocarbons,e.g. paraffin, polyethylene, rubber; metals or salts of metals having adensity over 2.2 g/cm³, e.g. copper, iron, calcium carbonate, bariumchloride, and lead nitrate.

The above-cited inert additives make it possible to increase the yieldof target products.

The present method envisages using materials to be transformed (carbonand boron nitride) in the form of various modifications, having variousfractional compositions. The latter circumstance allows the obtainingtarget products also with various fractional compositions. Performing ofthe method with the use of various inert additives at various pressuresand temperatures of detonation obtains target products of prescribedmodifications: diamond--of cubic modification or in the form of amixture of hexagonal (1 to 40%) and cubic (60 to 99%) modifications;boron nitride--of wurtzite modifications or as a mixture of cubic (1 to80%) and wurtzite (20 to 99%) modifications.

The present invention makes it possible to use components of the chargeboth in the form of fine-dispersed fractions and in the form of granulesprepared at least from one component of the charge or from variouscombinations of such components. The charge may be a mixture ofcomponents in the form of fine-dispersed fractions, or, in case ofgranules, the charge may

be a mixture of a fine-dispersed fraction of an explosive with granulesof a material to be transformed; or

consist of granules prepared from a mixture of an explosive with amaterial to be transformed and a fine-dispersed fraction of additivesinert to the material to be transformed; or

consist of a fine-dispersed fraction of an explosive and granulesprepared from a mixture of a material to be transformed with inertadditives; or

consist of granules prepared from a mixture of an explosive, a materialto be transformed and inert additives; etc.

Said granules may have various sizes and shapes: such as cylinders,disks, spheres, cubes, etc.

In the invention an embodiment of the method is envisaged, according towhich a charge is preliminarily enclosed in the shell made of substanceinert to a material to be transformed and soluble in water, acids andalkalies. Such a substance can be, e.g., sodium chloride, calciumcarbonate, or lead oxide. The presence of a shell from said substancecontributes to prolonging the time of action of high pressures andtemperatures on the material being transformed upon detonation of acharge.

The charge detonation may be effected in an atmosphere of air,preferably in an atmosphere of a gas inert to the target products (e.g.in an atmosphere of nitrogen, hydrogen, argon), in an atmosphere ofgaseous detonation products, or in a vacuum of 10⁻⁴ to 10 mm Hg.

PREFERRED EMDODIMENT OF THE INVENTION

Given hereinbelow is a description of a preferred embodiment of themethod of the invention, to be had in conjunction with the accompanyingdrawing, in which a steel container with a charge located therein areshown diagrammatically. Referring now to the drawing, in the walls of asteel container shown at 1 four openings 2, 3, 4 and 5 are made,provided with plugs 6, 7, 8 and 9. Opening 3 serves for fillingcontainer 1 with a gas inert to the target products. Opening 4 isintended for untightening container 1 after an explosion and forrelieving excess pressure conditioned by the evolution of gaseousdetonation products. Opening 5 is intended for discharging soliddetonation products after one explosion or after several explosions. Acharge 10 is mounted on a steel rod 11 (this rod may be made from someother material, such as wood or celluloid) secured in plug 6. In thesame plug two electrical lead-ins 12 are secured, intended for attachingthereto wires of a detonator cap 13 installed in charge 10.

For the present method to be realized, in case of producing diamond, amixture is prepared, consisting of 80 mass % of fine-dispersed hexogenand 20 mass % of oil furnace black with a specific surface of 15 m² /g,and from the resulting mixture a charge is shaped which is a cylinderhaving a diameter of 40 mm and a density of 1.5 g/cm³. The thus madecharge 10 is secured on steel rod 11 made fast in plug 6. Detonator cap13 is then inserted into the charge, and the detonator cap wires areconnected to lead-ins 12. After that the charge is placed into container1 and plug 6 is tightened. Said container is fit for multiple use(thousands and dozens of thousands of times). Through opening 3 liquidnitrogen is poured into the container with opening 5 being closed withplug 9. The liquid nitrogen evaporates at the bottom of container 1, andthe resulting gaseous nitrogen displaces air from the container throughopenings 3 and 4. Then plugs 7 and 8 are made tight, and charge 10 isdetonated by applying voltage to lead-ins 12. Then opening 4 isunplugged, and the pressure in the container is equalized with theatmosphere. After that, through opening 5 solid detonation products aredischarged, these products comprising diamond, non-converted carbon,fragments of the detonator cap, moisture, and absorbed gaseousdetonation products. Solid detonation products are treated with boilingnitric acid for the detonator cap fragments to be dissolved. Then thesolid detonation products are washed with water and treated with boilingperchloric acid till complete dissolution of the unconverted carbon. Thediamond remains unchanged. The insoluble precipitate is separated bycentrifugation and treated with a boiling solution of sodium hydroxideto remove silicate impurities. The precipitate is washed with water anddried. The yield of diamond is 17% of the amount of the initial black.The resultant product is a powder with a specific surface of 35 m² /g,particle size of 0.01 to 1.0 μm, fully consisting of particles ofcubic-modification diamond. According to the X-ray analysis data, thediamond particles are characterized by the size of coherent scatteringareas equal to 150 Å and by crystal lattice microdistortions of thesecond order Δa/a<5 ·10⁻⁴. Concentration of paramagnetic centers is1.05·10¹⁹ g⁻¹ (ESR data).

For the present method to be realized, where diamond-like modificationsof boron nitride are to be produced, 25 mass % of hexagonal boronnitride with a particle size less than 10 μm is mixed with 75 mass % offine-dispersed hexogen, and from the mixture thus prepared a cylindricalcharge is shaped having a diameter of 30 mm and a density of 1.75 g/cm³.The resulting charge 10 is secured on steel rod 11 made fast on plug 6.Detonator cap 13 is inserted into the charge, and the detonator capwires are connected to lead-ins 12. Then the charge is placed intocontainer 1 and plug 6 is tightened. Further plug 9 is tightened inopening 5, and through opening 3 the container is filled with gaseousnitrogen. Then plugs 7 and 8 are tightened in openings 3 and 4respectively and, by applying voltage to lead-ins 12, charge 10 isdetonated. By removing the plug from opening 4, the pressure in thecontainer is equalized with the atmospheric pressure, and throughopening 5 solid detonation products are discharged from the container,comprising diamond-like modifications of boron nitride, non-convertedhexagonal boron nitride, fragments of the detonator cap, moisture,absorbed gaseous detonation products, and an admixture of free carbon.Solid detonation products are treated with boiling perchloric acid untilcomplete dissolution of free carbon. Then solid detonation products aretreated in succession with boiling nitric acid and boiling perchloricacid to remove the detonator cap fragments and free carbon. Theinsoluble residue is treated with a mixture of concentrated sulphuricacid and sodium fluoride (mass ratio 20:3 respectively) at a temperatureof 200° C. to remove the non-converted boron nitride. The residue isisolated, washed with water and dried at a temperature of 100° C. Theproduct thus obtained is a mixture of cubic and wurtzite modificationsof boron nitride (70 mass % and 30 mass % respectively). The total yieldof diamond-like modifications of boron nitride is 15% of the initialhexagonal boron nitride. The resulting product is a powder with adensity of 3.20 g/cm³, consisting of particles having a size of 0.05 to3.0 μm.

The present method obtains diamond and diamond-like modifications ofboron nitride in the form of powders having the following properties:

    ______________________________________                                        Diamond                                                                       Particle size, μm                                                          graphite             0.05-5.0                                                 black                0.01-1.0                                                 Specific surface, m.sup.2 /g                                                                         10-120                                                 Density, g/cm.sup.3  3.15-3.40                                                Bulk weight, g/cm.sup.3                                                                            0.35-1.0                                                 Size of coherent scattering areas, Å                                                             85-200                                                 Crystal lattice microdistortions of                                                                  0-2.5 · 10.sup.-3                             the second order, Δa/a                                                  Concentration of paramagnetic                                                 centers, g.sup.-1 :                                                           graphite             (1.5-4.5) · 10.sup.19                           black                (1.0-1.3) · 10.sup.19                           Thermal stability in vacuum during                                                                 over 800                                                 30 minutes, °C.                                                        Weight losses on heating in vacuum                                                                 up to 5.0                                                to 800° C., mass %                                                     Diamond-like Modifications of Boron Nitride                                   Particle size, μm 0.05-5.0                                                 Density, g/cm.sup.3  3.15-3.30                                                Phase composition, %:                                                         cubic boron nitride    0-80                                                   wurtzite boron nitride                                                                               20-100                                                 ______________________________________                                    

For a better understanding of the present invention given hereinbeloware examples of its specific embodiment. In all cases the yield of thetarget product is given in per cent of the mass of a mixture consistingof the target product and non-converted starting material (15 to 20 mass% of the initial material to be transformed is oxidized during thecharge detonation).

EXAMPLE 1

A charge is shaped from a mixture consisting of 80 mass % offine-dispersed hexogen and 20 mass % of hexagonal graphite with aparticle size less than 300 μm. The charge is placed at the center of acontainer filled with nitrogen. The container is tightened, the chargeis detonated, and solid detonation products are discharged, consistingof diamond, non-converted carbon, fragments of a detonator cap,moisture, and absorbed gaseous detonation products. The solid detonationproducts are treated in succession with boiling nitric acid and boilingperchloric acid to remove admixtures and non-converted carbon. Theresidue is treated with a boiling solution of an equimolar mixture ofsodium hydroxide and potassium hydroxide to dissolve silicateadmixtures. The precipitate is separated by centrifugation, washed withwater and dried at a temperature of 130° C.

The resulting product is a diamond powder consisting of a mixture of 25mass % of hexagonal modification (lonsdaleite) and 75 mass % of cubicmodification. The size of powder particles is 0.1 to 3.0 μm. Pycnometricdensity is 3.25 g/cm³. Concentration of paramagnetic centers is 2.0·10¹⁹g⁻¹. The total yield of said modifications of diamond is 1.5 mass %.

EXAMPLE 2

A charge is shaped from 1.5 kg of a mixture consisting of 66 mass % offine-dispersed hexogen, 17 mass % of hexagonal graphite with particlesize of 40 to 250 μm, and 17 mass % of water. Operations are carried outas described in Example 1. Average dynamic pressure in the detonationwave front upon detonation of the charge is 8 GPa, average temperatureis about 3000° K.

The resulting product is a diamond powder consisting of a mixture ofcubic and hexagonal modifications (60 and 40 mass % respectively). Theproperties of the obtained product are similar to those of the productobtained as described in Example 1. The total yield of saidmodifications of diamond is 2.0 mass %.

EXAMPLE 3

From a mixture consisting of 75 mass % of fine-dispersed hexogen and 25mass % of glass carbon (size of glass carbon particles is 10 to 300 μm)a charge is shaped, having a density of 1.1 g/cm³. The charge isdetonated and subsequent operations are performed as described inExample 1. The resulting product is a diamond powder of cubicmodification with a particle size of 0.1 to 5.0 μm, specific surface of40 m² /g, density of 3.15 g/cm³. On heating lin vacuum at a temperatureof 800° C. the diamond loses 5 mass % of volatile admixture, but itscrystal structure remains unchanged. The yield of diamond is 1.7 mass %.

EXAMPLE 4

From a mixture of 990 g of fine-dispersed hexogen and 10 g of Ceylongraphite with a particle size of 50 to 200 μm, containing about 15-20%of rhombohedral modification a charge with a density of 1.0 g/cm³ isshaped. The charge is detonated and subsequent operations are performedas described in Example 1.

The resulting product is a diamond powder, consisting of 70% of cubicand 30% of hexagonal modifications. The properties of the diamond aresimilar to those of the diamond described in Example 1. The total yieldof said modifications of diamond is 5.0%.

EXAMPLE 5

From a mixture consisting of 85.7 mass % of fine-dispersed PETN and 14.3mass % of hexagonal boron nitride with particle size less than 10 μm, acharge is shaped. Upon detonation a dynamic pressure of 30 GPa and atemperature of about 5000° K. are developed in the detonation wavefront. The charge is placed at the center of a container and a vacuum of10 mm Hg is created in it. The charge is detonated and solid detonationproducts are then extracted from the container. These solid detonationproducts are a mixture of wurtzite modification of boron nitride, boronoxide, detonator fragments, moisture, absorbed gaseous detonationproducts, and admixtures of free carbon. The solid detonation productsare treated in succession with boiling nitrid acid and boilingperchloric acid to remove the detonator fragments and free carbon,respectively, as well as to remove boron oxide and absorbed gaseousdetonation products. Then the residue is treated with a mixture ofconcentrated sulphuric acid and sodium fluoride (in a mass ratio of 20:3respectively) at a temperature of 200° C. to dissolve the non-convertedhexagonal boron nitride. The insoluble residue is separated, washed withwater, and dried at a temperature of 100° C.

The product thus obtained is wurtzite modification of boron nitride witha particle size of 0.05 to 5.0 μm and a density of 3.15 g/cm³. The yieldof the product is 2.0%.

EXAMPLE 6

From a mixture consisting of 30 mass % of fine-dispersed hexogen and 70mass % of hexagonal boron nitride with a particle size less than 10 μm acharge is shaped. Upon detonation a dynamic pressure of 3 GPa and atemperature of about 2000° K. originate in the detonation wave front.The charge is detonated in an atmosphere of argon. Subsequent operationsof isolating the target product from solid detonation products aresimilar to those described in Example 5.

The resulting product is wurtzite modification of boron nitride withproperties similar to those of the product obtained in Example 5. Theyield of the product is 1.5%.

EXAMPLE 7

From a mixture consisting of 91 mass % of fine-dispersed hexogen and 9mass % of spherical granules of 0.5 to 1.0 mm in diameter, consisting of50 mass % of hexagonal boron nitride with particle size less than 5 μmand 50 mass % of ammonium chloride with a particle size of 1 to 100 μm acharge is shaped with an average density of 1.6 g/cm³. The charge isdetonated in the atmosphere of gaseous detonation products, which haveformed upon preliminary detonation of an identical charge. Subsequentoperations are similar to those described in Example 5.

The resulting powder-like product is a mixture of cubic and wurtzitemodifications of boron nitride (30 and 70 mass % respectively). Thepowder has a particle size of 0.5 to 3.0 μm and density of 3.30 g/cm³.The total yield of diamond-like modifications of boron nitride is 3.3%.

EXAMPLE 8

A mixture of paraffin, powdered copper (having a density of 8.9 g/cm³)with a particle size less than 40 μm, and natural hexagonal graphitewith a particle size less than 500 μm with the mass ratio thereof of1:1:1 is granulated, the result being spherical granules with a diameterabout 1 mm. From a mixture consisting of 85.7 mass % of fine-dispersedhexogen and 14.3 mass % of said granules a cylindrical charge is shaped.The charge detonation and subsequent operations are performed byfollowing a procedure similar to that described in Example 1.

The resulting product is a mixture of 40% of hexagonal and 60% of cubicmodifications of diamond. The size of the powder particles is 1 to 5 μm,specific surface is 10 m² /g, and density is 3.40 g/cm³. The total yieldof said modifications of diamond is 3.5 mass %.

EXAMPLE 9

A charge is shaped from a mixture of 1.0 kg of fine-dispersed hexogenand 0.2 kg of cylindrical granules consisting of 80 mass % of powderediron (having a density of 7.8 g/cm³) with a particle size less than 40μm and 20 mass % of hexagonal graphite with particle size less than 40μm, particle diameter of 5 mm and height of 5 mm. The charge isdetonated in an atmosphere of air. Operations for isolating the targetproduct from solid detonation products are similar to those described inExample 1.

The product thus obtained is a mixture of 70% of cubic and 30% ofhexagonal modifications of diamond. The properties of the resultingdiamond are similr to those of the diamond obtained in Example 8. Thetotal yield of said modifications of diamond is 5.0%.

EXAMPLE 10

A charge having a density of 1.1 g/cm³ is shaped from a mixtureconsisting of 10 mass % of oil furnace black with a specific surface of15 m² /g and 90 mass % of cylindrical granules having a diameter of 3 mmand a height of 10 mm, consisting of 95 mass % of fine-dispersed hexogenand 5 mass % of paraffin. The charge detonation and target productisolation operations are similar to those described in Example 1.

The resulting product is a diamond powder of cubic modification with aspecific surface of 35 m² /g, particle size of 0.01 to 1.0 μm, size ofcoherent scattering areas of 150 Å, crystal lattice microdistortions ofthe second kind of about 1·10⁻³, concentration of paramagnetic centersof 1.3·10¹⁹ g⁻¹. The yield of diamond is 3.5%.

EXAMPLE 11

A charge is shaped from a mixture consisting of 75 mass % oftrinitrotoluene with a particle size less than 200 μm, 24 mass % ofhexagonal boron nitride with a particle size less than 3 μm, and 1 mass% of hydrazine. The charge detonation is performed in a vacuum of 10 mmHg. The target product isolation operations are performed by following aprocedure similar to that described in Example 5.

The resulting product is a boron nitride powder of wurtzite modificationwith particle size of 0.1 to 1.0 μm and density of 3.20 g/cm³. The yieldof the product is 2.7%.

EXAMPLE 12

A charge having a density of 1.55 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen, 12.5 mass % ofhexagonal boron nitride with a particle size less than 10 μm, and 12.5mass % of copper dichloride dihydrate with a particle size less than 1μm.

The charge is detonated in an atmosphere of air. Solid detonationproducts consisting of wurtzite and hexagonal modifications of boronnitride, detonator fragments, copper dichloride decomposition products,moisture, absorbed gaseous detonation products and an admixture of freecarbon are treated with boiling nitric acid to remove the detonatorfragments and the copper dichloride decomposition products, washed withwater, dried, and treated with a mixture of concentrated sulphuric acidand sodium fluoride (in a mass ratio of 20:3 respectively) at atemperature of 200° C. to dissolve the non-converted hexagonal boronnitride. The residue is separated, washed with water and dried at atemperature of 100° C.

The resulting product is a wurtzite modification of boron nitride. Theproperties of the product are similar to those of the product obtainedas described in Example 11. The yield of the diamond-like modificationof boron nitride is 3.5%.

EXAMPLE 13

A charge having a density of 1.2 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen, 15 mass % ofpyrolytic carbon with a particle size less than 200 μm, and 10 mass % ofa saturated aqueous solution of hydrazine nitrate. The charge detonationand subsequent operations are performed in a manner similar to thatdescribed in Example 1.

The resulting product is a diamond powder having a composition andproperties similar to those of the powder described in Example 4. Theyield of diamond is 4.0%.

EXAMPLE 14

A cylindrical charge of 40 mm diameter and having a density of 1.4 g/cm³is shaped from a mixture cconsisting of 70 mass % of tetryl with aparticle size less than 300 μm, 20 mass % of oil furnace black with aspecific surface of 15 m² /g, and 10 mass % of octane. The charge isdetonated in an atmosphere of hydrogen. Subsequent operations aresimilar to those described in Example 1.

The powder-like product thus obtained is a diamond of cubicmodification. The density of the powder is 3.23 g/cm³ ; specificsurface, 40 m² /g; concentration of paramagnetic centers, about 1.2·10¹⁹g⁻¹ ; size of coherent scattering areas, 160 Å. The yield of diamond is5.0%.

EXAMPLE 15

A flat charge having a thickness of 5 mm, width of 100 mm and length of200 mm is shaped from a mixture consisting of 80 mass % of octogen witha particle size less than 500 μm, 10 mass % of schungite with a particlesize less than 100 μm, and 10 mass % of isoprene rubber. The chargedetonation and subsequent operations are performed in a manner similarto that described in Example 1.

The product thus obtained is a diamond powder of cubic modification,with properties similar to those of the diamond produced in Example 14.The yield of diamond is 5.5%.

EXAMPLE 16

A charge having a density of 1.5 g/cm³ is shaped from a mixtureconsisting of 80 mass % of fine-dispersed hexogen, 10 mass % of thermaloil black with a specific surface of 75 m² /g, and 10 mass % of asaturated aqueous solution of sodium chloride. The charge detonation andsubsequent operations are performed in a manner similar to thatdescribed in Example 1.

The resulting product is cubic diamond powder with a specific surface of77 m² /g. The thermal stability of the diamond thus produced exceeds800° C. The yield of diamond is 3.0%.

EXAMPLE 17

A charge having a density of 1.5 g/cm³ is shaped from a mixtureconsisting of 80 mass % of fine-dispersed hexogen, 10 mass % of thermaloil black with a specific surface of 75 m² /g, and 10 mass % of a 40%aqueous solution of calcium chloride. The charge detonation andsubsequent operations are performed by following a procedure similar tothat described in Example 1.

The product thus obtained is similar in its properties to the diamondobtained in Example 16. The yield of diamond is 3.0%.

EXAMPLE 18

A charge having a density of 1.8 g/cm³ is shaped from a mixtureconsisting of 60 mass % of fine-dispersed hexogen, 10 mass % ofhexagonal boron nitride with a particle size less than 10 μm, and 30mass % of calcium chloride hexahydrate. The charge detonation andsubsequent operations are performed in a manner similar to thatdescribed in Example 12.

The properties of the resulting product which is a wurtzite modificationof boron nitride are similar to those of the product obtained in Example12. The yield of wurtzite modification of boron nitride is 4.0%.

EXAMPLE 19

A charge having a density of 1.2 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen, 15 mass % ofpyrolytic graphite with a particle size less than 200 μm, and 10 mass %of hydrazine nitrate. The charge detonation and subsequent operationsare performed in a manner similar to that described in Example 1.

The resulting product is a diamond powder, having a composition andproperties similar to those of the powder described in Example 4. Theyield of diamond is 5.0%.

EXAMPLE 20

A charge having a density of 1.2 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen, 15 mass % ofpyrolytic graphite with a particle size less than 200 μm, and 10 mass %of hydrazine sulphate. The charge detonation and subsequent operationsare performed in a manner similar to that described in Example 1.

The resulting product is a diamond powder, having a composition andproperties similar to those of the product described in Example 4. Theyield of diamond is 4.5%.

EXAMPLE 21

A charge having a density of 1.2 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen, 15 mass % ofpyrolytic graphite with particle size less than 200 μm, and 10 mass % ofa 40% aqueous solution of hydrazine chloride. The charge detonation andsubsequent operations are performed in a manner similar to thatdescribed in Example 1.

The product thus obtained is a diamond powder, in its composition andproperties similar to that described in Example 4. The yield of diamondis 3.5%.

EXAMPLE 22

A charge having a density of 1.6 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen, 17 mass % ofhexagonal graphite, and 18 mass % of iron with a particle size of 40 to200 μm. The charge detonation and subsequent operations are performed ina manner similar to that described in Example 1.

The resulting product is a diamond powder of cubic modification with abimodal distribution of particle size: 0.05 to 0.05 μm (30 rel. %) and1.0 to 5.0 μm (70 rel. %). The concentration of paramagnetic centers isabout 4.5·10¹⁹ g⁻¹. The yield of diamond is 6.5%.

EXAMPLE 23

From a mixture consisting of 80 mass % of fine-dispersed hexogen and 20mass % of turbostratic boron nitride with a particle size less than 10μm, a cylindrical charge with a diameter of 40 mm is shaped, this chargebeing enclosed in a 20 mm-thick shell from sodium chloride. The chargeis detonated in a vacuum of 10⁻¹ mm Hg. Subsequent operations areperformed in a manner similar to that described in Example 5.

The resulting product is a powder, consisting of 80% of cubic and 20% ofwurtzite modifications of boron nitride. The yield of diamond-likemodifications of boron nitride is 15%. The properties of the powder aresimilar to those of the product obtained in Example 7.

EXAMPLE 24

From a mixture consisting of 80 mass % of octogen with particle sizeless than 300 μm and 20 mass % of sugar carbon with a particle size lessthan 300 μm a cylindrical charge with a diameter of 30 mm is shaped,this charge being then enclosed in a shell from pressed calciumcarbonate, having a thickness of 25 mm. The charge detonation andsubsequent operations are performed in a manner similar to thatdescribed in Example 1.

The resulting powder-like product is cubic modification of diamond witha particle size of 0.1 to 2.0 μm, density of 3.3 g/cm³, size of coherentscattering areas of 130 Å, crystal lattice microdistortions of thesecond kind less than 5·10⁻⁴, concentration of paramagnetic centres of1.35·10¹⁹ g⁻¹. The yield of diamond is 13.1%.

EXAMPLE 25

From a mixture consisting of 79 mass % of fine-dispersed hexogen and 21mass % of special-purity hexagonal graphite with a particle size lessthan 100 μm a cylindrical charge is shaped, having a diameter of 30 mmand a density of 1.58 g/cm³, said charge being then enclosed in a 20mm-thick shell from sodium chloride. The charge detonation andsubsequent operations are performed in a manner similar to thatdescribed in EXAMPLE 1.

The resulting product is a diamond powder of cubic modification with aparticle size of 0.05 to 5.0 μm, specific surface of 32 m² /g,density of3.40 g/cm³, size of coherent scattering areas of 85 Å, crystal latticemicrodistortions of the second kind of 1.5·10⁻³, concentration ofparamagnetic centres of 1.5·10¹⁹ g⁻¹. The yield of diamond is 15.1%.

EXAMPLE 26

A cylindrical charge having a density of 1.65 g/cm³ and a diameter of 30mm is shaped from a mixture consisting of 83 mass % of fine-dispersedhexogen and 17 mass % of hexagonal boron nitride with a particle sizeless than 10 μm. The charge is then enclosed in a shell from pressedlead oxide, having a thickness of 10 mm. The charge is detonated in anatmosphere of nitrogen. Solid detonation products are treated withboiling perchloric acid to complete removal of free carbon. Then theresidue is treated with boiling nitrite acid to dissolve detonator capfragments and lead oxides. The insoluble residue is treated with amixture of concentrated sulphuric acid and sodium fluoride (in a massratio of 20:3 respectively) at a temperature of 200° C. to dissolve thenon-converted hexagonal boron nitride. The precipitate is separated,washed with water and dried at a temperature of 100° C.

The resulting product is a mixture of cubic and wurtzite modificationsof boron nitride. Said product in its composition and properties issimilar to the product obtained in Example 23. The total yield ofdiamond-like modifications of boron nitride is 16%.

EXAMPLE 27

A charge having a density of 1.5 g/cm³ is shaped from a mixture of 150 gof fine-dispersed hexogen with a particle size less than 100 μm and 50 gof colloidal graphite. The charge detonation and subsequent operationsare performed in a manner similar to that described in Example 1.

The resulting product is a powder of diamond with a specific surface of120 g/m², size of coherent scattering areas of 130 Å, crystal latticemicrodistortions of the second kind less than 5·10⁻⁴, a concentration ofparamagnetic centers of 1.35·10¹⁹ g⁻¹. The yield of diamond is 10%.

EXAMPLE 28

A cylindrical charge having a diameter of 40 mm is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen and 25 mass % of blackproduced by thermal electrocracking from gas and having a specificsurface of 20 m² /g. The charge detonation and subsequent operations areperformed in a manner similar to that described in Example 1.

The product thus obtained is a diamond powder of cubic modification witha specific surface of 35 m² /g, size of coherent scattering areas of 170Å, crystal lattice microdistortions of the second kind less than 5·10⁻⁴,concentration of paramagnetic centers of 1.13·10¹⁹ g⁻¹. The yield ofdiamond is 8.5%.

EXAMPLE 29

A charge having a density of 1.5 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen and 25 mass % ofrefinery coke with a particle size less than 350 μm, heat-treated at1300° C. The charge detonation and subsequent operations are performedas in Example 1.

The resulting product is a diamond powder of cubic modification with aparticle size of 0.3 to 3.0 μm, density of 3.27 g/cm³, and the size ofcoherent scattering areas is 120 Å. The yield of diamond is 12.3%.

EXAMPLE 30

A cylindrical charge having a density of 1.6 g/cm³ is shaped from amixture consisting of 83 mass % of fine-dispersed hexogen and 17 mass %of spectrally pure hexagonal graphite. The charge is detonated in avacuum of 10⁻⁴ mm Hg. Subsequent operations are performed by following aprocedure similar to that described in Example 1.

The resulting product is a diamond powder of cubic modification, theproperties of which are similar to those of the product obtained asdescribed in Example 25. The yield of diamond is 20%.

EXAMPLE 31

A disk-shaped charge of 60 mm in diameter and having a thickness of 30mm is prepared from a mixture consisting of 79 mass % of fine-dispersedhexogen and 21 mass % of hexagonal boron nitride with a particle sizeless than 10 μm. The charge is detonated in an atmosphere of nitrogen,with simultaneous initiation by two detonator caps arranged at theopposite end faces of the disk and axially thereto. At the collisionboundary opposite detonation waves a dynamic pressure exceeding 60 GPaand a temperature of about 6000° K. is developed. Subsequent operationsare performed in a manner similar to that described in Example 5.

The product thus obtained is a powder mixture of cubic and wurtzitemodifications of boron nitride (70% and 30% respectively). The particlesize of the powder is within 0.05 to 3.0 μm, density is 3.3 g/cm³. Thetotal yield of diamond-like modifications of boron nitride is 15.0%.

EXAMPLE 32

750 g of hexogen is dissolved in dimethyl formamide and 250 g of oilfurnace black having a specific surface of 15 m² /g is dispersed in theresulting solution. The suspension thus obtained is poured into a10-fold quantity of water. The precipitated mixture of recrystallizedhexogen with a particle size less than 10 μm and black is filtered offand dried. From the resulting mixture a cylindrical charge having adiameter of 40 mm and a density of 1.5 g/cm³ is shaped. The chargedetonation and subsequent operations are performed by following aprocedure similar to that used in Example 1.

The resulting product is a diamond powder of cubic modification, havinga specific surface of 59 m² /g, size of coherent scattering areas of 200Å, crystal lattice microdistortions of the second kind less than 5·10⁻⁴,and concentration of paramagnetic centers of about 1.25·10¹⁹ g⁻¹. Theyield of diamond is 19.3%.

EXAMPLE 33

A tubular charge having a diameter of 100 mm, tube wall thickness of 10mm, and a density of 1.6 g/cm³ is shaped from a mixture consisting of450 g of fine-dispersed hexogen, 75 g of spectrally pure hexagonalgraphite with a particle size less than 200 μm, and 75 g of hexagonalboron nitride with a particle size less than 10 μm. The charge isdetonated in an atmosphere of nitrogen. Solid detonation products are amixture of diamond and diamond-like modifications of boron nitride,boron oxide, boron carbide, detonator fragments, moisture, and absorbedgaseous detonation products. Solid detonation products are treated withboiling nitric acid and with boiling perchloric acid in succession toremove the detonator fragments, boron oxide, non-diamond forms ofcarbon, and gaseous detonation products. The insoluble residue istreated with a mixture of concentrated sulphuric acid and sodiumfluoride (in a mass ratio of 20:3 respectively) at a temperature of 200°C., then separated, washed and dried.

The resulting product is a mixture of cubic modification of diamond,cubic modification of boron nitride and wurtzite modification of boronnitride in a mass ratio of 70:20:10 respectively. The total yield ofsaid modifications of the product is 15%.

EXAMPLE 34

A flat charge of 30 mm thickness, 60 mm in width and 200 mm length,having a density of 1.7 g/cm³ is shaped from a mixture consisting of 75mass % of fine-dispersed hexogen, 20 mass % of spectrally pure hexagonalgraphite with a particle size less than 40 μm, and 5 mass % of ammoniumnitrate. The charge detonation and subsequent operations are performedin a manner similar to that described in Example 1.

The resulting product is a diamond powder of cubic modification withproperties similar to those of the diamond powder produced as describedin Example 25. The yield of diamond is 22%.

EXAMPLE 35

A flat charge of 15 mm thickness, 30 mm width and 150 mm length isshaped from a mixture consisting of 80 mass % of fine-dispersed hexogenand 20 mass % of black obtained in a diffusion flame and having aspecific surface of 200 m² /g. The charge detonation and subsequentoperations are performed by following a procedure similar to thatdescribed in Example 1.

The resulting product is a diamond powder of cubic modification with anaverage particle size of 150 μm and the size is coherent scatteringareas of 140 Å. The yield of diamond is 10%.

EXAMPLE 36

A charge having a density of 1.2 g/cm³ is shaped from a mixtureconsisting of 75 mass % of fine-dispersed hexogen and 25 mass % ofnatural hexagonal graphite with a particle size less than 400 μm. Thecharge thus prepared is impregnated with liquid nitrogen, in an amountof 10% of the charge mass. The charge detonation and subsequentoperations are performed in a manner similar to that described inExample 1.

The product thus obtained is a diamond powder, consisting of 70% ofcubic and 30% of hexagonal modifications. The magnitude of the crystallattice microdistortions of the second kind for the cubic modificationin this product is 2·10⁻³. The specific surface of the powder is 30 m²/g. The total yield of said modifications of diamond is 5.0%.

EXAMPLE 37

A cylindrical charge of 40 mm diameter is shaped from a mixtureconsisting of 60 mass % of tetranitromethane, 20 mass % of oil furnaceblack having a specific surface of 15 m² /g, and 20 mass % ofnitrobenzene. The charge detonation and subsequent operations areperformed in a manner similar to that described in Example 1. Thedynamic pressure and temperature originating as a result of detonationof the charge of said composition are 12 GPa and 5000° K. respectively.

The product thus obtained is a diamond powder of cubic modification,similar in its properties to the diamond powder produced as described inExample 32. The yield of diamond is 15%.

EXAMPLE 38

Granules having a diameter of 5 mm, consisting of 80 mass % offine-dispersed hexogen, 15 mass % of spectrally pure hexagonal graphitewith a particle size less than 100 μm, and 5 mass % of polyethylene witha particle size less than 100 μm are mixed in a mass ratio of 3:1 withhexogen having a particle size less than 0.5 mm, and from the mixturethus prepared a charge is shaped, having an average density of 1.6g/cm³. The charge detonation and subsequent operations are performed byfollowing a procedure similar to that described in Example 1.

The resulting product is a diamond powder of cubic modification withproperties similar to those of the diamond powder obtained as describedin Example 30. The yield of diamond is 21%.

EXAMPLE 39

A charge having a density of 1.45 g/cm³ is shaped from a mixtureconsisting of 15 mass % of oil furnace black with a specific surface of15 m² /g, 80 mass % of fine-dispersed hexogen, and 5 mass % of benzene.The charge detonation and subsequent operations are performed in amanner similar to that described in Example 1.

The resulting product is a diamond powder of cubic modification,analogous in its properties to the product obtained as described inExample 14. The yield of diamond is 8%.

EXAMPLE 40

A cylindrical charge of 40 mm diameter is shaped from a mixtureconsisting of 40 mass % of fine-dispersed hexogen, 10 mass % ofhexagonal boron nitride with particle size less than 10 μm, and 50 mass% of barium chloride (density of 3 g/cm³) with a particle size less than500 μm. The charge detonation and subsequent operations are performed byfollowing a procedure similar to that described in Example 12.

The obtained product is a wurtzite modification of boron nitride withproperties similar to those of the product obtained in Example 12. Theyield of wurtzite modification of boron nitride is 5.0%.

EXAMPLE 41

A cylindrical charge of 40 mm diameter and having a density of 1.70g/cm³ is shaped from a mixture consisting of 30 mass % of fine-dispersedPETN and 70 mass % of glass carbon in the form of granules that areplates having a thickness of 1 mm and an average linear size of about 8mm. The charge detonation and subsequent operations are performed in amanner similar to that described in Example 1.

The resulting product is a diamond powder of cubic modification. Theyield of the product is 1.0%.

EXAMPLE 42

A cylindrical charge of 40 mm diameter and having a density of 1.3 g/cm³is shaped from a mixture consisting of 80 mass % of fine-dispersedhexogen, 1 mass % of turbostratic boron nitride (density, 2.9 g/cm³).The charge is detonated under a vacuum of 1 mm Hg. Subsequent operationsare performed as described in Example 5.

The resulting product is a boron nitride powder of wurtzite modificationwith properties similar to those of the product obtained in Example 5.The yield of the product is 3.5%.

INDUSTRIAL APPLICABILITY

Superhard materials produced by the method proposed herein can be usedboth as abrasives and as starting materials in the production ofpolycrystalline compacts from which cutting tools are manufactured.

What is claimed is:
 1. A method for producing diamond and/ordiamond-like modifications of boron nitride by detonating in acontainer, a charge of a particulate admixture of an explosive and thematerial to be transformed, said material to be transformed selectedfrom the group consisting of:(a) carbon to produce diamond, (b) boronnitride to produce diamond-like modifications of boron nitride, and (c)carbon and boron nitride to produce a mixture of diamond anddiamond-like modifications of boron nitride;wherein said explosive upondetonation produces dynamic pressures varying from about 3 to 60 GPa andtemperatures varying from about 2,000° to 6,000° K.
 2. The method claim1, wherein the material transformed is carbon.
 3. The method of claim 1,wherein the material transformed is boron nitride.
 4. The method ofclaim 1, wherein the material transformed is a mixture of carbon andboron nitride.
 5. The method of claim 1, wherein the charge contains 30to 99 wt. % of an explosive and 1 to 70 wt. % of the material to betransformed.
 6. The method of claim 1, wherein said charge also includesadditives inert to the material to be transformed, which evaporate anddecompose beyond the front of a detonation wave, in an amount of 1 to50% by weight of the charge.
 7. The method of claim 6, wherein the inertadditives are selected from the group consisting of water, dry ice,liquid nitrogen, aqueous solutions of metal salts, crystal hydrates,ammonium salts, hydrazine, hydrazine salts, aqueous solutions ofhydrazine salts, and liquid or solid hydrocarbons.
 8. The method ofclaim 1, wherein before detonation, the charge is enclosed in a shellmade of a substance inert to the material to be transformed and solublein water, acids or alkalis.
 9. The method of claim 1, wherein the chargeis detonated in an atmosphere of a gas inert to the transformedmaterial, or an atmosphere of gaseous detonation products, or in avacuum of 10⁻⁴ to 10 mm Hg.